The present invention relates to a hot gun repair refractory mix for a lining refractory. More particularly, the present invention relates to a hot gun repair refractory mix for a lining refractory in a refractory furnace such as a basic oxygen furnace, argon oxygen decarburization converter, electric arc furnace and the like and in trough running a molten pig iron, hot torpedo car and the like. Hereinafter the hot gun repair refractory mix is called a "gunning material".
Heretofore, it has been known that the penetration of a slag, molten iron, molten steel and the like into a structure of a refractory material can be defended effectively by the use of carbon.
Recently, the hot gunning repair utilizing a carbon bond has been considerably practiced in a steel manufacturing furnace such as a basic oxygen furnace, an argon oxygen decarburization convertor, an electric arc furnace and the like, where by a remarkable effect can be obtained.
As an example of a substance formed with a carbon bond, hitherto, there has been used organic resin such as tar pitch, petroleum pitch and phenol resin.
Generally, a typical composition of the well known hot repair gun refractory utilizing a carbon bond consists of coarse refractory particles, refractory fine powder, pitch and binder.
As an example, of a gunning material there is proposed a refractory composition (mostly a material to be gunned) including substantially non-acid refractory granules, 2 to 12% by weight of solid pitch granules having a softening point of 200.degree. F. (about 93.3.degree. C.) at least and having such granule diameter that substantially all the amount passed through a 4-mesh sieve and a substantial amount is retained on a 100-mesh sieve, 0.05 to 4% by weight of a plasticizer and 0.5 to 5% by weight of a water-soluble cold setting bonding component. However, there are defects that the solid pitch is so comparatively fine as to be melted by the furnace heat within a very short time and therefore the gunned material deposited on the furnace wall will flow away together with the molten pitch before being sintered.
As another example of a gunning material, there is proposed a gunning material which is gunned by a normally used dry-gun. The refractory granules are covered on the surface with a high melting point pitch and have less than several % by weight of a pitch of the same. The granules are mixed with less than several % by weight of the pitch of same quality granulated to a diameter of 0.3 to 2.0 mm. However, there are defects in that the steps of covering the granules with the pitch and granulating are required and the above steps are complicated and elevate the cost.
Even if these various proposals are utilized, however, there are the following points in question:
(1) smoke emitting is so much that the practice of these proposals is difficult,
(2) the slurry viscosity cannot be obtained, the abhesive rate is decreased, and
(3) the enrichment of carbon is limited.
Namely, the temperature within the furnace in the gunning operation is about 400.degree. C. to 1000.degree. C. and consequently smoke emission is considerable and the gunning practice is remarkably difficult. By the covering of the pitch on the fine granule of refractory, furthermore, the defects that the wetting of the fine granule with water, the adhesive rate is decreased and the life of the hot repair gun-operated portion cannot be sufficiently exhibited are considered.
As a result of making various examinations and research on the above-mentioned problems and on the elimination of said defects, the present inventors have succeeded in obtaining a gunning material wherein the granulated material obtained by covering of the refractory fine powder on the surface of the carbonaceous particle is mixed.
Namely, the main object of the present invention is to provide a gunning material having carbon granule-carbon bond wherein the penetration of slag, molten pig iron and molten steel into the lining rafractory is inhibited and the life of the hot repair gun-operated portion is considerably increased.
A further object of the present invention is to provide a gunning material wherein the smoke emission at the gunning operation time is nothing, the rebound loss is little and a minute structure is formed.
Therefore, the subject matter of the present invention is directed to a hot gun repair refractory mix characterized by comprising a granulated material which is preformed by covering the surface of carbonaceous substance particles with a fine powder of refractory.